基于关联度延拓Hilbert移相的配网电流互感器在线校验方法

On-line calibration method of current transformer for distribution network based on time series-weighted correlation degree extension Hilbert phase shift algorithm

配网低压电流互感器计量准确性直接影响配电网的安全稳定和经济运行,需实时掌握其运行状态。针对采用数字比较法的在线校验方法中,模数转换过程标准通道模数转换器存在固定延时难以完全补偿的问题,提出了一种时序加权关联度延拓结合4项3阶Nuttall窗的Hilbert精准移相算法,有效抑制了“端点效应”,实现了对模数转换器固定延时的精准移相。仿真实验表明该算法在频率偏移、谐波及噪声干扰下,移相偏差小于10^(-10),在此基础上研制了在线校验装置,该装置与离线校验装置比值误差偏差小于0.006%,能够满足0.2S级配网低压电流互感器在线校验的需求。

The measurement accuracy of low-voltage current transformer for distribution network directly affects the safe,stable and economic operation of distribution network,so it is necessary to grasp its operation status in real time.In the on-line calibration method of digital comparison method,the standard channel analog-to-digital converter in the analog-to-digital conversion process has a fixed delay and is difficult to fully compensate.Aiming at this problem,a Hilbert precise phase shift algorithm based on time series-weighted correlation degree extension combined with 4-term 3-derivative Nuttall window is proposed,which effectively suppresses the′end effect′and realizes the precise phase shift of the fixed delay of the analog-to-digital converter.The simulation results show that the phase shift deviation of the algorithm is less than 10^(-10) under the interference of frequency offset,harmonics and noise.On this basis,an on-line calibration device is developed.The ratio error between the device and the off-line calibration device is less than 0.006%,which can meet the requirements of on-line calibration for 0.2S-accuracy low-voltage current transformer for distribution network.